Hello,
I recently got a S. invicta colony from britishants with two queens and ~20w and I keep them in an escape proof acrylic nest (3d printed with modular design). The problem is, since yesterday I just can‘t find the second queen, so I think she either somehow escaped when I plugged in another arena or she was the weaker queen and so the still small colony killed and ate her. What is the best way to catch her in case she really escaped, of course she could also hide in some corner but I just looked everywhere. I hooked up a heated test tube nest nearby the colony in hope she will find back. My room is currently just about 12C warm so she couldn’t have been far away. What is the possibly best way to find her?

Queen ants are not usually very fast, and I think that it is unusual for a queen to travel alone. If al the other ants are there, why do you think that the queen escaped? If it did, and you manage to find it, you can just put it back in a test tube by bordering off an area with your hand and letting her in. If she is not alone, she is harder to catch.